Phase equilibria of the Mg-La-Nd system at 500 °C

The phase equilibria at 500 °C of the Mg-La-Nd system were investigated with four diffusion couples and 38 alloys, by means of X-ray diffraction technique, scanning electron microscopy and electron probe microanalyses. Five three-phase equilibria were accurately determined. The Mg2La phase, which is not stable at 500 °C in the Mg-La binary system, was found to be stabilized with the addition of Nd. The composition range of the ternary Mg2La phase was measured to be ∼0-12.6 at.% Nd at 500 °C. The Mg41La5 phase, which is not stable at 500 °C in the Mg-La binary system, is stabilized at 500 °C with the addition of Nd. The solubility of La in Mg41Nd5 was measured to be up to 7.4 at.% La. The solubility of Nd in Mg17La2 and in Mg12La was determined to be 1.4 at.% Nd and 5.1 at.% Nd, respectively. The continuous solid solutions Mg(La, Nd) and Mg3(La, Nd) form between MgLa and MgNd and between Mg3La and Mg3Nd, respectively. The isothermal section at 500 °C was constructed in the present work.